Jewelry is generally used as an ornament on the body or as a decorative item to improve the aesthetics, beauty, and intrinsic worth of an item. As an ornament, jewelry is generally worn on the body, such as earrings, necklaces, bracelets, etc. As a decorative item jewelry has been generally displayed with high-value items, such as artistic pieces. In such cases, jewelry may take the form of a frame or handle. Furthermore, the use of jewelry in personal and functional items, such as cell-phones, watches, glasses, guns and pistols, pens, faucets and plumbing is becoming more common. Such personal items have frequent contact with body parts, such as hands, and are subject to a more intensive “wear and tear” environment than other jewelry items.
Because of their attributed intrinsic worth, jewelry is generally made from precious metals such as gold, platinum, and palladium. Jewelry articles made of solid precious metals are quite common, although clad materials and veneered composites are also used to a certain degree. (Herein, jewelry is defined where the metallic component comprises at least a solid piece of precious metal alloy of more than 0.1 mm thickness. Thin-film surface coatings of precious metals are excluded from the jewelry definition, whereas jewelry comprising “veneer” or clad layers of precious metal alloys is included). Furthermore, jewelry is further enhanced in aesthetics, beauty and intrinsic worth by incorporating gemstones. Generally, it is desired that the content of precious metal in the jewelry alloy is above a minimum weight percentage such as 14 karat or 18 karat. Due to the attributed high worth of jewelry, expectations of the quality of jewelry articles are quite high. Jewelry articles are expected to be unique and exceptional in their design and they are expected to be fabricated and finished to very high standards. Even slight imperfections, subtle to the naked eye, are not generally tolerated.
Accordingly, the fabrication and finishing of jewelry articles is a highly tedious process and several challenges have yet to be satisfactorily resolved. The cast articles of precious metals generally lack the desired precision and need substantial effort in finishing operations. Furthermore, the incorporation of gemstone shows significant problems during casting and subsequent fabrication process in order to secure satisfactory and long-term fixing of gemstones firmly in place.
Jewelry articles are also expected to be durable and sustain long life. However, the common precious metal-based alloys have notoriously poor mechanical properties such as yield strength, hardness, and wear resistance. Furthermore, with the use of jewelry in personal items, such as cell-phones, watches etc, various physical and mechanical properties of precious metals have become more critical for the durability of jewelry products. The demand for high yield strength, hardness, corrosion and erosion resistance, and wear and scratch resistance in such products is so overwhelming for the common precious metal-based alloys that new novel solutions are greatly desired.